Open Doors listed top 50 countries where it is most difficult to practice the Christian faith, and categorized levels of persecution as "extreme", "very high" or "high".

The global level of Christian persecution has increased for the fourth year in a row, with Asian countries displaying a particularly rapid rise.

"Millions of Christians around the world now live their lives against varying levels of discrimination, discovery, violence and arrest," said Open Doors.

North Korea has been branded the most dangerous country in the world for Christians since 2002.

Dictator Kim Jong-un's vicious crackdown against the nation's estimated 300,000 Christians has allowed the country to remain on top of the list.

The dictator's family is worshipped like gods and any suggestion there is a higher authority than the supreme leader is "immediately crushed".

Of the top 20 countries on the list, 14 were due to increased hostility caused by Islamic extremism.

In Somalia, which ranks second for persecution, people even suspected of being a Christian can be killed on the spot.

"Tens of thousands of Christians are incarcerated in horrific labour camps, and thousands more keep their faith in Christ a complete secret - often their own family members do not know of their faith," said Open Doors.

In Afghanistan, which ranks third in the list, it is forbidden for Afghans to practice any faith other than Islam. However, thousands of Christians are living in the country.

"Discovered believers will sometimes be sent to a mental hospital, as families believe no sane person would leave Islam," said Open Doors.

India is ranked 15th on its list. Six states have already imposed anti-conversion laws to prevent anyone from practicing anything other than Hinduism. It is feared that the law will become national in the near future.

About 63.9 million Christians are living in India, and face persecution from the Hindu nationalist Bharatiya Janata Party (BJP).

"Some of those who have left Hinduism to follow Jesus have been attacked and even killed by their own parents," said Open Doors.